A 21-year-old man was fatally shot Sunday afternoon by what's believed to be an assault rifle in the Back of the Yards neighborhood, according to police.

Four men also were shot to death, and at least seven others, including a 3-year-old boy, have been wounded in separate shootings since Sunday evening on the city's South Side.

The 21-year-old, who police intially said was 17, was walking east in the 1700 block of West 46th Street around 1:30 p.m. when a light-colored, four-door Saturn pulled up and fired shots with a "high-powered semi-automatic weapon," striking the victim as he attempted to run, said Eugene Roy, chief of detectives for the Chicago police.

The victim's name is Salvador Suarez, of the 4500 block of South Hermitage Avenue, according to the Cook County medical examiner's office.

"There's literally dozens of shell casings on the street you can see marked by the orange cones," Roy said about the evidence markers. "This is indicative of the level of violence we see on a daily basis."

“Here’s yet another example of a weapon of war used to torment another U.S. city,’’ said Chicago police spokesman Anthony Guglielmi. “Terrible.’’

Police are investigating whether the gun, which is “possibly an AK-47,’’ has been used in any other shootings, Guglielmi said.

“It’s certainly unusual,’’ Guglielmi said of the assault weapon. “This is not the typical weapon used in a lot of shootings.''

Police gather at the scene after a 21-year-old man was shot to death with what's believed to be an assault rifle June 19, 2016, in the 1700 block of West 46th Street. (WGN-TV/Chicago Tribune)

Police gather at the scene after a 21-year-old man was shot to death with what's believed to be an assault rifle June 19, 2016, in the 1700 block of West 46th Street. (WGN-TV/Chicago Tribune)

The man shot did not have any identification on him when the attack occurred, so authorities can’t be sure who he is. A community event had ended shortly before the attack occurred, but Guglielmi said they could not be sure whether he was involved in the event or not.

“At least two people’’ were inside the four-door vehicle, possibly a Saturn crossover, that was involved, Guglielmi said. Someone inside fired “numerous rounds,’’ and he was hit “multiple times.” The weapon was not recovered.

The victim was pronounced dead on the scene, said Officer Michelle Tannehill, a police spokeswoman.

The shooting was believed to be gang-related, Roy said.

After the attack, a large group of community members gathered at the scene. As officers were getting there and investigating, someone made threats, leading to an extra-heavy police reaction, including a special operations response unit, Guglielmi said.

“Threats were made that they would harm officers on the scene," Guglielmi said.

Ald. Raymond Lopez, 15th, said Sunday's shooting happened about 20 feet from the front doors of Holy Cross Immaculate Heart of Mary about 10 minutes before church let out.

Outside, roughly 30 shell casings were scattered across West 46th Street, just outside of the large twin towers and pillared entrance of the Romanesque church.

Roy said police would be in touch with the Archdiocese of Chicago as well as Chicago Public Schools to ensure that students will be able to go to William H. Seward Communication Arts Academy Elementary School, less than a block away from the scene, on Monday.

At the perimeter of the crime scene, police stood guard wearing bulletproof vests and strapped with assault rifles as children with youth soccer league jerseys dribbled a soccer ball across the crosswalk.

About a dozen neighbors stood in the shade staring at the heavy police presence. Some, like Olivia Nuno, wept as they embraced each other.

Nuno, who grew up in the neighborhood but moved to Cicero three years ago, said she went to Sinclair Alternative High School with the victim.

"I'm not going to say he was an angel," Nuno said. "He did stupid stuff, but this neighborhood has a way of turning the best people into trash."

Neighbors say two rival gang factions, La Raza and the Saints, have been feuding in the neighborhood, contributing to the rash of recent shootings.

According to Lopez, gunfire erupted near 46th and Wood streets on Wednesday, but no one was hurt. Another shooting also took place at 43rd Street and Marshfield Avenue on Tuesday, but there were no fatalities. Lopez said he believes they are all related.

In the most-recent fatal shooting:

About 1:30 a.m. Monday, a 22-year-old man died after being shot in the Grand Crossing neighborhood on the South Side, said Officer Veejay Zala, a police spokesman. The man, Eugene Singleton of the 700 block of East 84th Place, was in the 7300 block of South University Avenue when he was shot in the head and back, authorities said. He was taken to Northwestern Memorial Hospital, where he was later pronounced dead, Zala said.

About 12:50 a.m., a man died after being shot in a shooting in the Englewood neighborhood on the South Side, said Officer Jose Estrada, a police spokesman. The man was in the 1500 block of West 69th Street when he was shot in the lower back and chest. He was taken in critical condition to Advocate Christ Medical Center in Oak Lawn and was later pronounced dead, Estrada said.

Editor's note, June 28: The man was later identified as Ramal Hicks, 34, of the 7700 block of South May Street. He was pronounced dead at 3:55 a.m. after suffering multiple gunshot wounds, according to the Cook County medical examiner's office.

About 10:40 p.m. Sunday, a 21-year-old man was shot to death on Lake Shore Drive downtown and was driven to the Bronzeville neighborhood on the South Side where he was abandoned, Zala said. Detectives believe the man was shot in the 600 block of South Lake Shore Drive in the lower back. He was then dropped off in the first block of East 35th Street in Bronzeville, where first responders were called to, police said. The man was taken to Northwestern Memorial Hospital in critical condition and was later pronounced dead, Zala said.

About 6:50 p.m., a 21-year-old man died after he showed up with gunshot wounds at St. Bernard Hospital, Zala said. The man was identified as Otis Richmond, of the 5200 block of West Harrison Street, according to the medical examiner's office. The man managed to get to the hospital with a gunshot wound to his abdomen. He was later pronounced dead. It was not immediately known where the man was shot, Zala said.

In other non-fatal shootings:

A 24-year-old man walked into Northwestern Memorial Hospital about 6:10 a.m. after he was shot in the left buttocks earlier in the morning. He told police he was shot between 4:30 and 5 a.m. at a beach near 4300 South Lake Shore Drive. Three men walked up and one of them shot him.

At 3:40 a.m. Monday, a 33-year-old man was wounded in a shooting in the Lawndale neighborhood on the West Side, Zala said. The man was in the 700 block of South Kildare Avenue when he was shot in the arm. He was taken to Mount Sinai Hospital in good condition, Zala said.

About 2 a.m., a 23-year-old man was wounded in a shooting in the Back of the Yards neighborhood on the South Side, Zala said. The man was exiting the passenger side of a vehicle in the 1200 block of West 48th Street when someone in a white Jeep Liberty pulled up, got out and fired shots, Zala said. The man was hit in the right hand and right arm. He was taken to Stroger Hospital in good condition, Zala said.

About 11:30 p.m., a 25-year-old man was wounded in a shooting in the Englewood neighborhood on the South Side, Zala said. The man was on a sidewalk outside in the 7200 block of South May Street when an unknown attacker emerged from a gang way across the street and fired shots, striking the man in the foot. The man was taken to Holy Cross Hospital, where his condition stabilized, Zala said.

About the same time, about 11:30 p.m. Sunday, a 17-year-old boy was wounded in another shooting also in the Englewood neighborhood on the South Side, Zala said. The teen was in the 6700 block of South Green Street when he was shot in the left hand. He was taken to Stroger Hospital in good condition, Zala said.

About 10:45 p.m., a 25-year-old man and a 19-year-old man were wounded in a shooting at an outdoor gathering in the Washington Park neighborhood on the South Side, Zala said. The two men were at a gathering outside in the 5800 block of South Wabash Avenue when they were shot, Zala said. The 19-year-old was shot in the left leg. He was taken to Stroger Hospital, where his condition stabilized. The older man was hit in the right wrist, and he was taken to St. Bernard Hospital, where his condition stabilized, Zala said.

About 6:15 p.m., a 3-year-old boy was shot in the right shoulder near East 61st Street and South Kimbark Avenue in the Woodlawn neighborhood, police said. The boy was in a car seat when an unknown offender fired shots at the car, police said. People in the vehicle managed to get the boy to University of Chicago Hospital, and he was then transferred to Comer Children's Hospital in critical condition.